Synthesis of B vitamins by excised parts of white lupine seedlings grown in sterile culture.

In the thirties and early forties, numerous investigations were made on the vitamin requirements for growth of excised roots, stem tips, leaf sections, and embryos. As these experiments have been thoroughly reviewed by Bonner and Bonner (l), Robbins (2), and White (3), they will not be discussed here. If, in these experiments, the addition of a vitamin to the nutrient culture increased the growth, it was presumed that this vitamin was needed by the plant under consideration, and that the explants did not synthesize enough for their needs. If, on the other hand, there was no increase in growth, when a particular vitamin was supplemented to the medium, there were two explanations open to the investigator. Either this vitamin was not required for the growth process, or the plant synthesized enough of the vitamin for its needs. Direct determination of vitamin synthesis by excised roots have also been made. These investigations showed the synthesis of thiamine by pea roots (4), riboflavin by roots of tomato, clover, alfalfa, sunflower, and Daiura (5), and ascorbic acid by tomato roots (6). The purpose of this investigation has been to extend the knowledge of the ability of excised plant parts to synthesize thiamine, riboflavin, and niacin from the simple organic compounds, sucrose and glycine, and inorganic compounds, when grown in sterile culture.